Patent applications US 2004/0136901 and WO 2007/002599 relate to the general technological background.
Application US 2004/0136901 describes the reforming of a feedstock that can be carried out according to the three methods described above. For an autothermal reforming, the feedstock is mixed with a gas that contains oxygen (which can be pure oxygen, oxygen-enriched air, or air) in an O2/C ratio of typically between 0.3 and 0.8, and with steam according to an H2O/C ratio of typically between 0.1 and 3.0.
According to application WO 2007/002599, the steam reforming of a light feedstock such as methanol, ethanol, methane, ethane, propane, etc., is typically carried out with an H2O/C ratio of between 2 and 4. For heavier feedstocks, such as gasoline or diesel, this ratio can, in exceptional cases, reach 10.
Among documents in the prior art, patent application US 2006/0133992 describes a process for autothermal reforming of certain hydrocarbons that produce the hydrogen that is used for a fuel cell.
There are also patent documents that relate to reforming catalysts that specify ranges of operating conditions for the use of these catalysts:
Patent application US 2006/0111457 describes an autothermal reforming catalyst that is based on cerium oxide, and zirconium oxide and platinum oxide, and that operates with an O2/C ratio of between 0.1 and 0.8 and the H2O/C ratio of between 1 and 3.
Likewise, patent application US 2003/0060363 describes an autothermal reforming catalyst that is based on ruthenium, cerium oxide, and aluminum oxide and that operates with an O2/C ratio of between 0.1 and 0.5, preferably between 0.2 and 0.4, and the H2O/C ratio of between 0.1 and 5, and preferably between 0.5 and 3.0.
U.S. Pat. No. 6,749,828 describes an autothermal reforming catalyst that is based on ruthenium and zirconium and that operates with an O2/C ratio of between 0.1 and 1, preferably between 0.2 and 0.8, and the H2O/C ratio of between 0.1 and 10, preferably between 0.4 and 4.
Patent application US 2006/0093550 describes a very particular reforming catalyst that comprises nickel, cobalt, cerium, magnesium, and yttrium and that operates with an O2/C ratio of between 0.01 and 0.6, preferably between 0.4 and 0.6, and the H2O/C ratio of between 0 and 10, preferably between 0 and 2.
In contrast, patent application US 2004/0156778 describes a method for producing hydrogen-rich gas from hydrocarbon. In this method, hydrocarbon is brought into contact with air, water and a partial oxidation catalyst (POX). The entering flows have to comply with an O2/C ratio of between 0.02 and 0.15 and an H2O/C ratio of between 1 and 5.